tracing/events: Add trace_define_common_fields()

Extract duplicate code. Also prepare for the later patch.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A8BAFB8.1010304@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/ftrace_event.h

@@ -142,6 +142,7 @@ extern int filter_current_check_discard(struct ftrace_event_call *call,
 
 extern int trace_define_field(struct ftrace_event_call *call, char *type,
 			      char *name, int offset, int size, int is_signed);
+extern int trace_define_common_fields(struct ftrace_event_call *call);
 
 #define is_signed_type(type)	(((type)(-1)) < 0)
 
@@ -166,11 +167,4 @@ do {									\
 		__trace_printk(ip, fmt, ##args);			\
 } while (0)
 
-#define __common_field(type, item, is_signed)				\
-	ret = trace_define_field(event_call, #type, "common_" #item,	\
-				 offsetof(typeof(field.ent), item),	\
-				 sizeof(field.ent.item), is_signed);	\
-	if (ret)							\
-		return ret;
-
 #endif /* _LINUX_FTRACE_EVENT_H */

include/trace/ftrace.h

@@ -299,11 +299,9 @@ ftrace_define_fields_##call(struct ftrace_event_call *event_call)	\
 	struct ftrace_raw_##call field;					\
 	int ret;							\
 									\
-	__common_field(int, type, 1);					\
-	__common_field(unsigned char, flags, 0);			\
-	__common_field(unsigned char, preempt_count, 0);		\
-	__common_field(int, pid, 1);					\
-	__common_field(int, tgid, 1);					\
+	ret = trace_define_common_fields(event_call);			\
+	if (ret)							\
+		return ret;						\
 									\
 	tstruct;							\
 									\

kernel/trace/trace_events.c

@@ -62,6 +62,28 @@ int trace_define_field(struct ftrace_event_call *call, char *type,
 }
 EXPORT_SYMBOL_GPL(trace_define_field);
 
+#define __common_field(type, item)					\
+	ret = trace_define_field(call, #type, "common_" #item,		\
+				 offsetof(typeof(ent), item),		\
+				 sizeof(ent.item),			\
+				 is_signed_type(type));			\
+	if (ret)							\
+		return ret;
+
+int trace_define_common_fields(struct ftrace_event_call *call)
+{
+	int ret;
+	struct trace_entry ent;
+
+	__common_field(unsigned short, type);
+	__common_field(unsigned char, flags);
+	__common_field(unsigned char, preempt_count);
+	__common_field(int, pid);
+	__common_field(int, tgid);
+
+	return ret;
+}
+
 #ifdef CONFIG_MODULES
 
 static void trace_destroy_fields(struct ftrace_event_call *call)

kernel/trace/trace_export.c

@@ -189,11 +189,9 @@ ftrace_define_fields_##call(struct ftrace_event_call *event_call)	\
 	struct args field;						\
 	int ret;							\
 									\
-	__common_field(unsigned char, type, 0);				\
-	__common_field(unsigned char, flags, 0);			\
-	__common_field(unsigned char, preempt_count, 0);		\
-	__common_field(int, pid, 1);					\
-	__common_field(int, tgid, 1);					\
+	ret = trace_define_common_fields(event_call);			\
+	if (ret)							\
+		return ret;						\
 									\
 	tstruct;							\
 									\